The present invention relates to a wind energy plant having at least one rotor blade with a pitch angle, the pitch angle being adjustable by means of a pitch controller. Further, the wind energy plant has a generator converter unit, at least one electrical quantity of the generator converter unit being adjustable by means of a converter controller. The wind energy plant has a power train beginning with a rotor carrying the at least one rotor blade. The power train continues with a rotor shaft connected to the rotor. The rotor shaft is coupled to a gear, the output shaft of the gear leads into the generator.
The technical term pitch angle of a rotor blade is also called “blade angle”, so that the pitch controller may also be called “blade angle controller”.
The power output of the wind energy plant in the rated power range is mainly controlled by means of the rotation speed set point. In this case, the regulation is performed by a converter controller, sometimes also being called main converter controller. The regulation approach currently used in wind energy plants takes into account the rotation speed of the generator as a signal source for the converter controller. The precision of the rotation speed of the generator is highly dependent on different influencing factors, because the measured rotation speed of the generator as a rule interferes with oscillations of the power train, resiliences of the gear, oscillations of the machine carrier and tolerances in a clutch means, if provided. Up to now, in order to suppress theses influencing factors in the rotation speed of the generator, a strong filtering and damping of the measured values was performed. In particular, the measured values of the rotation speed of the generator were smoothed and in certain frequency bands partly eliminated. In the past, the so-filtered values of the rotation speed of the generator were applied also to a pitch controller, in order to adjust the pitch angle in dependency on the rotation speed of the generator. In particular in wind energy plants with large rotor diameter, the filtered values of the rotation speed of the generator led to a slow, sluggish behaviour of the pitch angle regulation.
The invention is based on the technical problem to provide a wind energy plant with a regulation of the pitch angle allowing for a dynamic regulation of the pitch angle, without interfering with the regulation of the converter more often than necessary.